While he praised the Australian garden for its style and message of sustainability, he said other gardens were much more expertly executed and were more thoughtful and innovative in terms of garden design.

“If that garden was better than the Telegraph garden, I’m a Dutchman,” he said.

Mr Bradley-Hole said the judges, who are all experts from the RHS, are not necessarily best qualified to judge and suggested fashion designers and other figures at the “top of their game” from the gardening or art world could be brought in to make the panel more expert.

Mr Bradley-Hole also said the system of judging did not allow garden design to be appreciated properly.

His garden this year was designed to be a “garden of the soul” that was viewed over time by an individual but he was judged on one group viewing.

He said that the Best in Show suggests it is the best garden and others are second best but in fact it is only the opinion of the judges.

Instead it should be called "Judges' Choice", he said, to reflect the award is for something the judges appreciate above all other gardens.

“Maybe there should not be a Best in Show because you are saying other gardens are second rate,” he said. “And quite often you are comparing apples and pears.”

Mr Bradley-Hole insisted it was not just sour grapes because his garden did not win - although he felt that the whole team did make an "outstanding garden".

"I think it is extremely unfortunate this year they have chosen a best garden that in my mind is not the best garden.

"Our garden was an outstanding garden perfectly executed."

Behind the scenes many designers and followers of the Chelsea Flower Show agree with Mr Bradley-Hole.

But Bob Sweet, head of judging at the RHS of shows, said the judging system has recently undergone a thorough review to ensure transparency and expertise.

The rules are now clearly presented to designers so they are aware of what they are being judged on and have an opportunity to give feedback.

He pointed out that the seven judges looking at the show gardens are all trained and qualified. There are also “observers” who do not judge but ensure the system is fair.

“The winning garden is chosen by the judges panel and is a vote of all the judges and it is a majority vote," he said.

"There was a unanimous decision that this year that the award should go to Fleming’s. In terms of the aspects of that decision, the judges choose the garden that in their view is best in all aspects I think they have very carefully considered their choice.”